Intro to the PNS: Spinal Cord and Spinal Nerves Flashcards
What does the PNS consist of?
Spinal nerves and cranial nerves
What is the spinal cord a continuation of?
The medulla through the foramen magnum
Where does the spinal cord end?
L1/L2 interspace
What is the end of the spinal cord called before it becomes cauda equina?
Conus medullaris
How many pair of spinal nerves are there?
31
How many spinal nerves are there per section of the vertebral column?
8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral, 1 Coccygeal
What is a spinal nerve composed of?
Fused ventral and dorsal root
What type of nerves are the ventral and dorsal nerves respectively?
Motor and sensory
What is the nomenclature for spinal nerves from C1-C7?
They are named for the vertebrae below from where they come out (C1 comes out above Cv1)
Where does C8 emerge?
Below C7
What is the nomenclature for spinal nerves other than C1-C8?
The are named for the vertebrae above from which the emerge (L5 emerges below Lv5)
What are the three layers of covering over the CNS from superficial to deep?
Dura mater, arachnoid mater, pia mater
What is unique about the pia mater?
It is directly attached to the brain/spinal cord much like skin
What connects the pia mater to the dura mater?
Denticulate ligaments
What is the white matter mostly consisting of?
Axons and no cell bodies
What is the grey matter mostly consisting of?
Cell bodies and no axons
What is found in the dorsal portion of the spinal cord?
Dorsal median septum which houses the posterior spinal vein
What is found in the ventral portion of the spinal cord?
Ventral median fissure with the anterior spinal artery running along the surface
What does the dorsal root ganglion consist of and what do they do?
Pseudounipolar neurons getting input from sensory cells and relaying them up to the brain
What does the ventral horn of the consist of and what do they do?
Alpha motor neurons that send signals to innervate muscles
What do the ventral and dorsal root come together to form?
Spinal nerves
What do spinal nerves quickly split into?
Dorsal and ventral ramii
What does the dorsal ramus innervate?
Dorsal surface of head neck and back
What does the ventral ramus contain?
Both sensory and motor neurons
What does the ventral ramus innervate?
Torso and limbs
What do ventral ramii form when they criss-cross?
A plexus that shares axons
